Kinetic modelling of total organic carbon degradation in dairy wastewater

Several treatment strategies have been proposed to minimize the environmental impact of dairy wastewaters. However, their complex and variable composition makes it difficult to predict the degradation kinetics of organic compounds. In this study, we used a mathematical approach to describe the kinetics of total organic carbon degradation in real dairy wastewater by photo-Fenton oxidation. The reactions were conducted under different ultraviolet light intensities, pH, temperature and Fenton reagent concentrations, obtaining a maximum TOC removal of 90.84%. The kinetic model was developed based on well-established photo-Fenton reactions. The present approach considers that account that small and large molecules of unknown contaminants are present in the effluent, and the smaller molecules are consumed first. The specific degradation rate (kd) was considered as an exponential function of total organic carbon conversion, comprising this effect of molecular size distribution on the treatment process. Fitting of experimental data to model predictions provided mean R2 values of 0.843-0.953.

Solar photo-Fenton oxidation of mature landfill leachate: empirical model and chemical inferences

In this study, a stochastic model was applied to investigate the degradation of landfill leachate by solar photo-Fenton processes. The coefficient of determination (R²) between experimental and predicted data ranged from 0.9958-0.9995. The optimal conditions for the initial phase (lasting 5-22 min) were high Fe²⁺ level, low pH level, and intermediate H₂O₂ level. For the second phase, optimal leachate degradation percentages were obtained by maintaining the pH, increasing H₂O_2, and decreasing Fe²⁺ to the lowest level. Determination of optimal reaction conditions (such as pH, Fe²⁺, and H₂O₂ values) for both degradation phases is of paramount importance for process scale-up. The major contribution of this study was the development of a tool that considers the effects of one or more reactions on organic carbon degradation. This was achieved by assessing the significance of the effects of experimental conditions on model parameters for the fast and slow steps of leachate degradation by advanced oxidation processes.